This invention relates to a binding lace for use in binding a material to be bound, and more particularly to a cable harness by means of an automatic binder developed by the present inventors.
Hitherto, cable harnesses are widely used for electric connections, for instance in electric equipment, in automatic telephone switchboards, air planes, or automobiles. At the present times, these cable harnesses are manually prepared by using fine fibers or nylon laces. In other words, a lace is wound around a group of cables at least two turns, and then tightened fast to form a knot by pulling the opposite free ends of the lace. In this respect, such binding or tightening operation requires a force of over 5 to 10 kg, so that the hands of an operator are sometimes injured and in addition there results a large range of differences in the condition of the lace thus bound, with the accompanying shortcoming of poor operational efficiency. In order to avoid these shortcomings, there has been proposed a binding or tightening tool which tightens around a material to be bound a plastic band having tightening ring portions at its opposite ends. More particularly, the plastic band is wound around the material one turn, and then, the tightening ring portions, through which the ends of the band are passed, are tightened together by means of a tightening tool by a given tightening force. This type tool is a partial success in improving the operational efficiency and consistent quality of bound portions or knots, but the plastic bands are costly, so that in case binding portions are tremendously large in number, an increase in expense is no longer negligible and presents a critical economical problem, unlike the less expensive use of the prior art fine fiber, nylon lace and the like.
For binding a material to be bound with a binding lace for cable harnesses by an automatic binder, the binding lace should be at least required to meet the following criteria.
First, the binding lace should be capable of running stably along guide channels of a lace guide while it is sent into the lace guide by means of a feed-in mechanism.
Secondly, the binding lace should be capable of holding the condition in which it is guided along the guide channels to form a loop around the bound material.
Thirdly, the binding lace should be capable of being tightened with ease around the bound material and the loops formed therewith should be concentrated in a narrow range.
Fourthly, the binding lace should be capable of holding stably the opposite ends thereof between loop portions and provide a reliable binding.
However, since binding laces which are well known are circular in cross section and have smooth surfaces since they are produced by extrusion, the binding surfaces slip with respect to each other to decrease rapidly the tightening force in binding a bounded material.
Further, an elastic force which could change the diameter of a binding lace is not given to the binding lace, so that a looseness of a knot cannot be avoided. To avoid the above looseness after binding, binding laces which are provided with a rough surface are proposed. These binding laces however are not capable of elastic recovery when the tightening force is added to the binding laces to avoid looseness after binding.
On the other hand, a vinyl chloride lace has not given a strong tension and a nylon lace has given a strong tension, but has easily slipped and loosened.